Combined outboard motor support and trim plate

ABSTRACT

An adjustable trim plate can be incorporated on the transom bracket of an outboard motor jack plate having right and left transom bracket members and right and left motor bracket members, by eliminating or modifying a lower cross-member of the motor bracket to provide clearance for an actuator connected to an upper transom bracket cross-member.

FIELD OF THE INVENTION

This invention relates to outboard marine propulsion, and more particularly to improvements in which an adjustable trim plate is incorporated in an outboard motor support.

BACKGROUND OF THE INVENTION

An outboard motor for marine propulsion typically comprises an internal combustion engine housed in a cowl, a driveshaft extending downward from the engine through a driveshaft housing, and a propeller located adjacent the lower end of the driveshaft housing and connected to the driveshaft through a set of gears. The driveshaft housing is ordinarily provided with a cavitation plate, above the propeller, to prevent air from reaching, and impairing the efficiency of, the propeller.

The motor is typically designed so that it can be attached directly to the transom of a boat. However, the effectiveness of a cavitation plate depends on how far it is below the surface of the water, and also on the speed of the boat. Therefore, there has been a demand for devices for adjusting the height of a cavitation plate. A device known as a “jack plate,” is commonly used to attach an outboard motor to the transom of a boat, and allows adjustment of the height of the motor, and consequently the height of its cavitation plate in order to achieve optimum performance. U.S. Pat. No. 6,305,996, dated Oct. 23, 2001, describes an advanced form of jack plate, comprising a transom bracket, a motor bracket, guides providing for vertical sliding of the motor bracket relative to the transom bracket, and an adjusting screw for manual control of the height of the motor bracket. Other similar jack plates have hydraulic or electromechanical actuators for remote control of the motor height.

Another factor affecting the performance of an outboard motorboat is a phenomenon known as “hole shot.” On start-up, especially at full throttle, the bow of the boat tends to rise out of the water. It is desirable to minimize the time during which the bow is raised so that boat accelerate. The bow may remain raised for several, e.g. as many as six or more, seconds, until the boat reaches a speed at which the bow settles to its normal cruising position. To reduce the time during which the bow is raised, actuator-operated trim plates have been used. Trim plates are ordinarily hinged to the transom of the boat on both sides of the outboard motor. By lowering the trim plate for a short time during start-up, hole shot time can be reduced significantly. The trim plates can then be raised for running at ordinary speeds, and can be lowered again at high speeds to keep the bow down. One disadvantage of conventional trim plates is that they are hinged on the boat transom, making installation difficult. another disadvantage is that the trim plates are separate from each other, making control complicated. A third disadvantage is that the effective area of the trim plates is limited because they cannot interfere with the driveshaft housing.

Attempts have been made to mount a trim plate on a jack plate, but these attempts have not been entirely successful because, in most jack plates, there is no convenient place to attach a trim plate actuator. The moving part of the jack plate, that is, the part to which the motor is attached directly, occupies the space that is needed for an actuator. Therefore, in order to provide a trim plate on a boat equipped with a jack plate, more elaborate jack plate and jack plate control configurations have been used.

SUMMARY OF THE INVENTION

Objects of this invention, therefore include simplification of the structure and mounting of a trim plate, providing for a larger and more effective trim plate, and providing for attachment of a combination jack plate and trim plate assembly as a unit to the transom of a boat.

We have discovered that, by utilizing a jack plate configuration similar to that of U.S. Pat. No. 6,305,996, we can easily incorporate a trim plate and a trim plate actuator into jack plate, and achieve the full benefits of both the jack plate and the trim plate in a simple structure that can be supplied, and attached to a boat transom, as a single unit. Although the outboard motor support in accordance with the invention preferably incorporates a jack plate for engine height adjustment as well as a trim plate, certain advantages of the invention can be realized in an embodiment in which the trim plate is provided on a non-adjustable engine set-back bracket that does not have a height adjustment feature. That is, the structure may consists primarily of opposed left and right members, a cross member, a trim plate pivoted to the left and right members, and an actuator connected to the trim plate and the cross-member.

In a simple embodiment of a combined outboard motor support and trim plate in accordance with the invention, a bracket assembly for attachment of an outboard motor to the transom of a boat comprises right and left members and at least one cross member rigidly connected to both of the right and left members and extending from one member to the other. A trim plate is pivoted to the bracket assembly about a horizontal pivot axis, and is located below, and spaced from, the cross member. The trim plate is pivotally movable about the pivot axis through a range of attitudes by an actuator connected to the trim plate and the cross member, so that the attitude of the trim plate can be adjusted independently of the height of the outboard motor.

When an outboard motor is attached to the combined outboard motor support and trim plate, the trim plate extends from a location on the port side of the engine to a location on the starboard side of the engine and part of the trim plate is disposed directly underneath the engine and forward of the drive shaft.

In a preferred embodiment, the bracket assembly includes a transom bracket for attachment to the transom and a motor bracket for attachment to the outboard motor. The right and left members of the bracket assembly are components of the transom bracket, and the height of the motor bracket relative to the transom bracket is adjustable. More particularly, in the preferred embodiment of the invention, the transom bracket comprises right and left bracket members and at least one cross member rigidly connected to both bracket members and extending from one of the bracket members to the other. The motor bracket is connected to the transom bracket and constrained to upward and downward movement relative to the transom bracket through a limited range. An adjuster is provided for adjusting the height of the motor bracket relative to the ransom bracket. A trim plate is pivoted to the transom bracket about a horizontal pivot axis, and is located below, and spaced from, the cross member. The trim plate is pivotally movable about the pivot axis through a range of attitudes, and an actuator connected to the trim plate and the cross member, controls the attitude of the trim plate independently of the height of the outboard motor.

Other objects, details and advantages of the invention will be apparent from the following detailed description when read in conjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a rear elevational view of a combined jack plate and trim plate in accordance with the invention;

FIG. 2 is a bottom plan view thereof, with the trim plate removed;

FIG. 3 is a side elevational view thereof as seen from the starboard side; and

FIG. 4 is a side elevational view showing the combined jack plate and trim plate installed on the transom of a boat and supporting an outboard motor.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The combined outboard motor support and trim plate in accordance with a preferred embodiment of the invention is seen from the aft side in FIG. 1. The principal elements of the combination are a transom bracket comprising right and left L-shaped bracket members 10 and 12 and a cross-member 14, and a motor bracket comprising right and left L-shaped bracket members 16 and 18, and a cross-member 20. Bracket members 10 and 16 are in sliding engagement with each other, as are bracket members 12 and 18, and the brackets are constrained for relative vertical sliding by bolts 22 and plates 24, as shown in FIG. 2. Details of the constraint mechanism may be found in U.S. Pat. No. 6,305,996, which is here incorporated by reference in its entirety. A screw 26 is threaded into cross-member 14 and rotatable, but axially constrained, in cross-member 20. The distance between cross-members 14 and 20 can be adjusted by rotation of the screw, for example, by means of a wrench (not shown) engaged with screw head 27, for adjustment of the height of the motor bracket relative to the transom bracket.

As describe thus far, the mechanism is substantially the same as that of U.S. Pat. No. 6,305,996. For improved rigidity, a second motor bracket cross-member 28 may be provided to connect the lower parts of the motor bracket members 16 and 18. However, this second motor bracket cross-member corresponds to the lower motor bracket cross member shown in U.S. Pat. No. 6,305,996, but is optional, and, if provided, should be located forward to the extent necessary to provide clearance for an actuator 30, or a recess 32 may be provided in bracket 28 for clearance.

A trim plate assembly 34 is composed of a mounting plate 36, which is connected to brackets 10 and 12, a hinge leaf 38 bolted to mounting plate 36, and a trim plate 40 pivotally connected to the hinge leaf 38 for tilting about a horizontal axis 42 (FIG. 3).

By eliminating the lower motor bracket cross member of U.S. Pat. No. 6,305,996 altogether, or by modifying it either by positioning it forward or providing a recess, it becomes possible to mount an actuator 30 in the manner shown in FIGS. 1 and 3. The actuator is hinged to the transom bracket cross member 14 by a clevis 44, and hinged to the trim plate by a clevis 46. The actuator shown is a hydraulic actuator having a cylinder 48 and a piston 50. However, other forms of actuators, for example electric motor driven linear actuators may also be used. In most cases, the actuator will be controllable from the helm by a suitable hydraulic or electrical remote control (not shown).

As shown in FIG. 4, the combination jack plate and trim plate is secured to the transom 52 of a boat 54, and supports an outboard motor 56 through a swivel 58. Part of the engine 60 of the outboard motor is directly above the trim plate and the outboard motor drive shaft housing 62 is directly behind the trim plate. In the embodiment shown in FIG. 4, the swivel is designed to set the motor back from the motor bracket. When a set back is provided, a large trim plate can be used without interference between the rear edge of the trim plate and the outboard motor's drive shaft housing. If the set back is small, a smaller trim plate may be used.

The combined jack plate and trim plate may be supplied as a fully assembled unit, including the motor bracket and the transom bracket, the height adjusting screw, the actuator and the trim plate. Moreover, the unit can be attached to the boat transom in a fully assembled condition. The fore-and-aft dimension of the trim plate will depend on the set back distance of the motor with which the unit is to be used. It is a simple matter, however, to replace the trim plate with another trim plate of a different size.

Following installation of the combined jack plate and trim plate, the motor height will ordinarily be adjusted by applying a wrench to screw head 27 so that the cavitation plate 64 (FIG. 4) on the outboard motor is at the proper height. In some cases, the motor height will be adjusted during operation of the boat for optimum performance. For this purpose, a separate actuator may be used in place of the wrench-actuated screw 26, as shown in U.S. Pat. No. 5,484,311, or a crank may be used as shown in U.S. Pat. No. 5,964,627.

In operation, when starting at full throttle, or near full throttle, the trim plate 40 is tilted downward to produce a negative pitch to counteract the positive pitch which would otherwise be imparted to the boat by the propeller thrust. In this way “hole shot” is controlled and excessive rise of the bow of the boat is prevented. As the forward speed of the boat increases, the trim plate can be raised to reduce drag. Even while traveling, and especially at high speed, the trim plate may be adjusted to keep the bow of the boat down.

Various modifications can be made to the combined motor support and trim plate described above. For example, Because the trim plate is hinged to, and located behind, the transom bracket, it can be supplied in any desired length in the direction of its pivot axis, and full advantage can be taken of the available space, in the widthwise direction, behind the transom of the boat. That is, it no longer necessary to provide trim plates on the transom of the boat, on both sides of the jack plate.

As pointed out previously, certain of the advantages of the invention can be realized in an embodiment in which the outboard motor support is not vertically adjustable. In such a case, it is still possible for a trim plate to be hinged to the outboard motor support, located directly behind the support, but in front of the motor drive shaft, and adjusted by an actuator connected to the trim plate and to a cross-member extending from a left bracket member to a right bracket member.

Still other modifications may be made to the apparatus and method described above without departing from the scope of the invention as defined in the following claims. 

1. A combined outboard motor support and trim plate comprising: a bracket assembly for attachment of an outboard motor to the transom of a boat the bracket assembly comprising right and left members and at least one cross member rigidly connected to both of said right and left members of the bracket assembly and extending from one of said members to the other; a trim plate pivoted to the bracket assembly about a horizontal pivot axis, the trim plate being located below, and spaced from, said cross member, and pivotally movable about said pivot axis through a range of attitudes; and an actuator connected to the trim plate and the cross member, for controlling the attitude of the trim plate independently of the height of the outboard motor.
 2. A combined outboard motor support and trim plate, according to claim 1, in which said bracket assembly includes a transom bracket for attachment to the transom of a boat and a motor bracket for attachment to an outboard motor, in which said right and left members are components of said transom bracket, and in which the height of said motor bracket relative to said transom bracket is adjustable.
 3. A combined outboard motor support and trim plate, according to claim 1, in combination with an outboard motor comprising an engine, a propeller, and a driveshaft extending vertically from the engine to the propeller, in which the trim plate extends from a location on the port side of the engine to a location on the starboard side of the engine and in which a part of the trim plate is disposed directly underneath the engine and forward of the drive shaft.
 4. A combined adjustable outboard motor support and trim plate comprising: a transom bracket for attachment to the transom of a boat the transom bracket comprising right and left bracket members and at least one cross member rigidly connected to both said bracket members and extending from one of said bracket members to the other; a motor bracket for attachment to an outboard motor, the motor bracket being connected to the transom bracket and constrained to upward and downward movement relative to the transom bracket through a limited range; an adjuster for adjusting the height of the motor bracket relative to the ransom bracket; a trim plate pivoted to the transom bracket about a horizontal pivot axis, the trim plate being located below, and spaced from, said cross member, and pivotally movable about said pivot axis through a range of attitudes; and an actuator connected to the trim plate and the cross member, for controlling the attitude of the trim plate independently of the height of the outboard motor.
 5. A combined outboard motor support and trim plate, according to claim 4, in combination with an outboard motor comprising an engine, a propeller, and a driveshaft extending vertically from the engine to the propeller, in which the trim plate extends from a location on the port side of the engine to a location on the starboard side of the engine and in which a part of the trim plate is disposed directly underneath the engine and forward of the drive shaft. 